1. Field of the Invention
The present invention relates to an electrolytic regeneration device for electrolytic regeneration of treatment liquid used in desmearing treatment in a manufacturing process for production of printed circuit boards or the like.
2. Description of the Background Art
When through holes or via holes are formed in a resin substrate used for a printed circuit board, smear, which is a resin debris, is generated by friction heat of a drill or laser and the resin. In order to maintain electric connection reliability of printed circuit boards, it is necessary to remove by a chemical treatment method or the like (desmearing treatment) the smear generated in through or via holes.
A solution of a permanganate such as sodium permanganate and potassium permanganate is typically used as a treatment liquid in the chemical treatment method. The treatment liquid is stored in a desmearing treatment tank. Where the resin substrate is immersed in the treatment liquid in the desmearing treatment tank to perform the desmearing treatment, the smear is oxidized and removed from through or via holes, and the permanganate in the treatment liquid is converted into a manganate. In order to reuse the treated treatment liquid for smear removal, electrolytic regeneration is performed that converts the manganate contained in the treatment liquid into the permanganate.
The conventional electrolytic regeneration device includes an electrolytic regeneration tank that stores the treatment liquid, electrodes immersed into the treatment liquid in the electrolytic regeneration tank, a feed-side conduit for feeding the treatment liquid discharged from the desmearing treatment tank into the electrolytic regeneration tank, and a return-side conduit for feeding the treatment liquid subjected to the electrolytic regeneration into the desmearing treatment tank. The treatment liquid circulates between the desmearing treatment tank and the electrolytic regeneration tank. In such an electrolytic regeneration device, a plurality of electrodes is usually disposed to increase the regeneration efficiency (see, for example, Japanese Patent No. 3,301,341).
However, with the configuration in which a plurality of electrodes is thus provided in the electrolytic regeneration tank, the volume of the electrolytic regeneration tank should be increased (to a value that is by a factor of about 1 to 2 larger than that of the desmearing treatment tank). As a result, a large installation area for arranging the electrolytic regeneration tank should be ensured and the bath volume increases.